1. Field of the Invention
The present invention relates to a generator related to wave power, especially to a negative-pressure wave generator.
2. Description of the Prior Arts
In the field of generators powered by waves, many techniques have been sophisticatedly developed. Those techniques also have been put into commercial application or practically installed in the sea. Said generator techniques include various types, such as hydraulic, Oscillating Water Column (OWC), overtopping, and so on.
The hydraulic generator technique adopts a hydraulic system, which transfers the wave energy into rotation mechanism energy, and then the rotation mechanism energy is used for power generation. The transferring efficiency may reach the expectation in the early stage. But the hydraulic system includes dedicated actuating mechanism, such as hydraulic cylinders and pistons. The continuous and non-stop wave movements may cause wear to the mechanism. In addition, since the hydraulic value in the tube often remains in a high-pressure range, the components also may have leakage problems. Therefore, after working for a period of time, the transferring efficiency gradually drops, and the cost of maintenance is increased.
The Oscillating Water Column generates power by the wave oscillation, which makes the water stream in a tube oscillating and pushing the air flow. Advantages include that this type is simple in structure, rarely has a breakdown, and the main equipments do not directly contact the seawater, thereby facilitating ease in maintenance. However, since the air is lower than the sea water in density, the transferring efficiency is lowered.
The overtopping generator generates power by storing the wave that is over a ramp in a tank floating on the sea. The water level of the tank must be higher than the sea level by at least three meters, thereby generating power by the difference in water level. This type of generator rarely breaks down, and is easy in maintenance. However, the overtopping generator needs wave higher than three meters to reach the transferring efficiency, and there are very few sea areas that can regularly have such high waves.
In addition, another type of generator generates power by the difference between the peaks and valleys. Water flows from high to low, forming a one-way flow to drive the generator. This type is simple in structure and has lowered maintenance cost. However, power can only be generated by half of the height of the wave, that is, the transferring efficiency is low.
To overcome the shortcomings, the present invention provides a negative-pressure wave generator to mitigate or obviate the aforementioned problems.